How to calculate CTR, CPC and CPA for your campaign
An ad report is full of numbers, but the question that matters is simple: how much did you pay per order? Five metrics answer it, and all of them come from four numbers found in any report: impressions, clicks, spend and conversions.
The five metrics, simply
- CTR, click-through rate: how many clicks per 100 impressions. It measures how appealing the ad is.
- CPC, cost per click: spend divided by clicks.
- CPM, cost per thousand: spend for every 1000 times the ad was shown.
- CPA, cost per acquisition: spend divided by orders or conversions. Usually the one that matters most.
- Conversion rate: how many conversions per 100 clicks. It measures the product page more than the ad.
10,000 impressions, 250 clicks, spend of 500 and 20 conversions.
CTR = 250 ÷ 10,000 × 100 = 2.5%, and CPC = 500 ÷ 250 = 2.00.
CPM = 500 ÷ 10,000 × 1000 = 50.00, and CPA = 500 ÷ 20 = 25.00.
Conversion rate = 20 ÷ 250 × 100 = 8%.
The cheapest click can cost the most
Compare that ad with a second one: 8,000 impressions, 400 clicks, spend of 600 and 12 conversions. Its CTR is 5%, double the first, and its CPC is only 1.50. It looks better, but its conversion rate is 3% and its CPA is 50.00, twice the first ad. The second ad brings lots of visitors who do not buy. So judge an ad by cost per acquisition, not cost per click.
How to do it
- Copy impressions, clicks and conversions for one period from your campaign report.
- Enter them in the Campaign performance calculator with the spend for the same period and the currency.
- Read the five metrics. A metric whose denominator is zero shows as “Undefined” with the reason.
- Watch for warnings: more clicks than impressions, or more conversions than clicks.
Limits to know
- The tool only calculates from the numbers you type, and does not connect to any ad platform.
- What counts as a “click” or a “conversion” differs between platforms. Take numbers from one source and one period.
- Conversion rate here is conversions ÷ clicks. Some platforms divide by sessions, so the figure may differ from your report.
Cost per acquisition alone does not tell you whether you are profitable. Enter your sales value and margin in the ROAS calculator to see the return you need to cover the ads. To know which link brought the conversion, tag your campaign links with the UTM campaign link builder.
Common questions
What is a good CTR?
There is no single right number for every platform and sector. Compare your ads with each other and with your past results, and in the end judge by cost per acquisition.
Why does my conversion rate differ from the platform report?
Because the tool divides by clicks, and some platforms divide by sessions or visits.
Are my numbers saved?
No, the calculation runs inside your browser and nothing is sent.